The injection-molding technique is one of the most important methods in plastics processing. It comprises countless variants of the production of solid or hollow products composed of one component or multiple components, with or without a prefinished insertion part.
EP 1612024 A1 discloses a method for producing a composite component, which has a carrier component and a cover component composed of plastic, and an armoring component disposed between these components, using the injection-molding technique. In this connection, the carrier component and the cover component are injected onto the armoring component in an injection-molding machine, one after the other. To implement the method, two possible injection-molding machine variants are proposed. In the first machine variant, the injection-molding machine comprises two mold mounting plates that can be moved relative to one another, with sub-tools mounted on them, and a turning unit disposed between the mold mounting plates, having a third sub-tool that can be rotated about an axis of rotation that extends transverse to the closing axis; a first cavity, which is delimited by the first and the third sub-tool, is used for injection-molding of the carrier component, while the cover component is injection-molded in a cavity delimited by the second and the third sub-tool. The intermediate product produced in the first step, consisting of the armoring component and the carrier component injection-molded onto it, is conveyed, after the tool is opened, adhering to the third sub-tool, by means of rotation of the latter, in front of the second sub-tool, before the tool is closed again for the second step. In the second machine variant, no turning unit is provided between the mold mounting plates that carry the first and the second sub-tool; instead, here one of the two mold mounting plates can be rotated about an axis of rotation parallel to the shooting axis. The different cavities are delimited, in each instance, by the first and the second sub-tool.
An injection-molding machine that corresponds to the second machine variant according to EP 1612024 A1, which serves, in the same manner, for producing a composite component having an insertion part around which injection-molding takes place on both sides, can also be derived from WO 2010/050101 A1.
WO 2009/143600 A1 discloses an injection-molding machine that corresponds, in terms of its fundamental construction, to that of the first machine variant according to EP 1612024 A1.
In various application areas, there is a need for plastic molded parts having an embedded barrier layer. This particularly holds true in the sector of foods packaging and (reclosable) containers, specifically when it is a matter of preventing the diffusion of oxygen into the interior of a plastic packaging in order to protect sensitive foods, or, in the case of technical substances, of preventing diffusion of volatile components out of the substance. Reference is made to the prior art, for example to WO 2010/139566 A1.
From cost aspects, a special challenge lies in being able to produce such plastic molded parts reliably and with process security, in which parts the barrier layer embedded in the plastic has only a minimal thickness.